Airbags are occupant restraining devices, which typically include a flexible envelope or “bag” that is designed to inflate rapidly during a collision in order to prevent the vehicle's occupants from striking interior objects located in front of (or, in some cases, on the side of) the occupant. In automobiles, airbags are designed to prevent occupants from striking the steering wheel, the vehicle door, a window, or any other interior objects. In aircraft, airbags are designed to prevent passengers from striking the seat in front each passenger, the tray tables, a window, or any other interior objects. Airbags on passenger rail cars (such as trains, monorails, trolleys), motorcycles, and other passenger transport vehicles work similarly.
Most modern vehicles contain multiple airbags. For example, most automobiles provide an airbag in front of each occupant seating position (at least in the front seat), to protect the head and torso. They may also contain knee airbags, which protect the occupant's knees and legs. Most aircraft provide airbags either positioned in the back of each seat (so as to deploy for the passenger sitting behind that seat) or in the seat belts. (For example, passengers sitting in the front seat or bulkhead in the aircraft do not have a seat in front of them, so in this instance, the airbag may be positioned in the passenger seat belt.) Passenger vehicles may also contain airbags in side locations, which can inflate between an occupant and the vehicle door or the vehicle window or wall.
Typically, sensors deploy one or more airbags in an impact zone at variable rates based on the type and severity of impact. Most airbags are designed to only inflate in moderate to severe frontal crashes. Airbags are normally designed with the intention of supplementing the protection of an occupant who is correctly restrained with a seatbelt.
Airbags are typically designed as large bags that require a large volume of gas for their inflation. They are typically round in shape, or peanut shaped, often formed by sewing two or three panels together in order to form a balloon or peanut shape.
Since their invention in the early 1950's and introduction in the mid-1970's, airbags have continually been improved upon. However, further airbag improvements are desirable, including airbags that have varying designs for varying types of seating arrangements in passenger vehicles.